Ace tends not to stock the really small screws we use in vapes. You can get them online at specialist places like McMaster Carr, but you have to know the size. And the type of thread, metric or SAE. I think all the ones I've needed for vapes have been metric.
You can get metal plates with threaded holes in lots of sizes, so you can try your screws in the holes and get the size. Don't know how expensive they are.
McM Carr sell screws in bags of 25 or more so it would be expensive to order multiple sizes just to try them out. I had to do that once though. Got lucky on the second bag. Maybe if the ones you tried from Ace were a little too large you could order the next size down from McM Carr.
Once you figure out the size make sure you get SS, other types of metal tend to not be hard enough. Actually they come in 2 different grades of SS, whichever one is slightly more expensive is the tougher one.
Maybe that Amazon bag is the way to go. At least it might be a fairly cheap way of finding out the size you need.
Hope I didn't just tell you a bunch of stuff you already knew.
good luck
Have you any plans today?
